Method for multi-reading a plurality of id&#39;s

ABSTRACT

A interrogator  1  specifies the maximum read range (S 0 , e 0 ) in which IDs to be read may exist (Step S 1 ), and the interrogator  1  transmits a read request command to transponders  2  (Step S 2 . When there is/are a response/responses, it is judged if the response(s) is/are from a single transponder  2  or multiple transponders  2  (Step S 5 ). When identifying multiple responses, an exponent e of the read range (S, e) is updated to e′=e−1 (Step S 6 ). When identifying a single response, ID of the transponder  2  that responded is read out (Step S 8 ) and the start S of the read range (S, e) is updated to S′=S+d (= 2   e ) (Step S 9 ). When a previous response flag F is not set to “multiple responses received”, the exponent e of the read range (S, e) is updated to e′=e+1 (Step S 13 ).

TECHNICAL FIELD

This invention relates to a method for multi-reading a plurality ofIdentifiers (IDs), wherein an interrogator and multiple transpondersrepeat queries and responses there between in order that theinterrogator discriminates unique ID given to each one of thetransponders.

BACKGROUND ART

Commercial production of Radio Frequency Identification tag (RFID tag)aiming at discriminating IDs by contactless means succeeds one another,and its application is expected in various fields, such as merchandisemanagement, individual attestation, and forgery prevention of banknotesor negotiable securities.

Particularly when the RFID tag is utilized at cash registers insupermarkets, convenience stores etc., it will effectively reducenecessary numbers of staffs and client's waiting time at cash registers,since checkout can be instantly performed without the need for takingout goods one by one, thereby improving operational efficiency andquality of customer service.

Discernment of IDs is performed when a transponder responds its ID to aquery from an interrogator, thus it is necessary to query eachtransponder individually. However, when multiple transponders are in thesame communication area, their responses collide making it impossible todiscriminate their IDs. Therefore, response requirements are specifiedin the queries so as to make only the transponders meeting therequirements make responses to the queries. Since there is notransponder with the same ID, the most efficient method of preventing acollision by way of setting the response requirements is to utilize IDsof the transponders themselves as response requirements.

In order to discriminate IDs by this method, the interrogator needs toquery every one of existing transponders to make them respond their IDs.However, it is not practical to use this method in a place like asupermarket, where a vast quantity of goods is dealt with, because it isextremely time consuming to query IDs of all the goods in thesupermarket every time a customer checkout their purchases at a cashregister.

In order to solve this problem, various multi-reading methods have beenproposed, but in these conventional methods, an interrogator queries thesymbols 1/0 in each of the binary digits (bits) which constitute ID inorder, and when its response disagrees with the query, further responsesfrom the transponder having that ID is forbidden. The interrogator readsout IDs of the transponders that remain until the last one by one asdetection numbers. For this reason, the conventional methods areproblematic in that more queries become necessary as the bit lengthbecomes long, requiring a long time to read one ID and even much longertime to read numbers of IDs of all the transponders.

Further disadvantageously, a write-in processing will be necessary onthe transponders with the conventional methods in order to forbidunwanted responses, and this requires additional costs for necessaryparts and overhead for the write-in processing.

One object of the present invention is therefore to provide a method formulti-reading a plurality of IDs, which can efficiently discriminate IDsin a short time even if the bit length is long, and which does not needthe write-in processing on the transponders.

SUMMARY OF THE INVENTION

To attain this object, claim 1 of the present invention comprises amethod for multi-reading a plurality of IDs, wherein an interrogator andmultiple transponders repeat queries and responses there between inorder that the interrogator discriminates unique ID given to each one ofthe transponders; and

-   -   wherein said interrogator when querying specifies a read range        of IDs, and permits a response from only the transponders whose        IDs are within said read range.

The method for multi-reading a plurality of IDs according to claim 2 asdescribed in claim 1, wherein said transponders when responding returntheir IDs, comprising the steps of:

-   -   1) when there is a plurality of responses to the query of said        interrogator, reducing the size of said read range by half in        the subsequent query;    -   2) when there is a single response to the query of said        interrogator, reading out ID of the transponder which responded        as well as shifting said read range to the following rank in the        subsequent query; and further when there is a single response or        no response to the previous query, expanding the size of said        read range d twice; and    -   3) when there is no response to the query of said interrogator,        shifting said read range to the following rank in the subsequent        query; and further when there is a single response or no        response to the previous query, expanding the size of said read        range d twice;    -   whereby the above mentioned steps are repeated until searching        of all the read ranges in which IDs to be read may exist is        completed.

The method for multi-reading a plurality of IDs according to claim 3 asdescribed in claim 1, wherein said transponders when responding returnsonly response signals, comprising the steps of:

-   -   1) when there is a response/responses from said transponders to        the query of said interrogator, and        -   1.1) when the size of said read range d is not equal to 1,            reducing the size of said read range d by half in the            subsequent query;        -   1.2) when the size of said read range d is equal to 1,            reading out ID of the transponder which responded as well as            shifting said read range to the following rank in the            subsequent query; and further when there is a            response/responses to the previous query and the size of            said read range d is equal to 1 or when there is no            response, expanding the size of said read range d twice; and    -   2) when there is no response from said transponders to the query        of said interrogator, shifting said read range to the following        rank in the subsequent query; and further when there is a        response/responses to the previous query and the size of said        read range d is equal to 1 or when there is no response,        expanding the size of said read range d twice;    -   whereby the above mentioned steps are repeated until searching        of all the read ranges in which IDs to be read may exist is        completed.

In the method for multi-reading a plurality of IDs according to claim 4as described in claims 2 and 3, the size of said read range d is definedby 2^(e), i.e. the power of 2, and said read range d is specified by aninteger value of either the start S or the end E of said read range dand exponent e of said read range d.

In the method for multi-reading a plurality of IDs according to claim 5as described in claim 4, the reduction value (d/2) of the size of saidread range d is calculated by exponential function, e=e−1.

In the method for multi-reading a plurality of IDs according to claim 6as described in claim 4, the expansion value (2×d) of the size of saidread range d is calculated by exponential function, e=e+1.

In the method for multi-reading a plurality of IDs according to claim 7as described in claim 4, the end E of said read range is calculated byformula E=S+2^(e)−1 when said read range is specified by the start S ofsaid read range and the exponent e.

In the method for multi-reading a plurality of IDs according to claim 8as described in claim 4, the start S of said read range is calculated byformula S=E-2^(e)+1 when said read range is specified by the end E ofsaid read range and the exponent e.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the multi-read system of multiple IDsaccording to the present invention;

FIG. 2 is a flow chart of the method for multi-reading according to thepresent invention wherein the transponder returns its ID to the query ofthe interrogator;

FIG. 3 is a flow chart of the method for multi-reading according to thepresent invention wherein the transponder returns only a response signalto the query of the interrogator;

FIG. 4 shows how the read range changes in the sequential read commands;and

FIG. 5 is a processing sequence chart of the method for multi-reading aplurality of IDs according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Some preferred embodiments of the present invention are described belowwith reference to the accompanying drawings.

A block diagram of the multi-read system of multiple IDs according toone embodiment of the present invention is shown in FIG. 1. In themulti-read system of multiple IDs, wireless data communication andelectric power transmission are operated between an interrogator 1 and atransponder 2 to discriminate IDs of the transponders 2 in order.Although the system disclosed here discriminates ID given to a wirelesscards and RFID tags etc., the multi-read system of the present inventionis not limited thereto, but it is also applicable to other systems whichdiscriminate telephone numbers of cellular phones in a service area, IDsgiven to terminals linked to LAN, etc.

The interrogator 1 consists of an antenna 11; an analog circuitcomprising a RF part 12, a transmitting part 13, and a receiving part14; and a digital circuit comprising a data-processing part 15. Theinterrogator modulates a read signal of ID and discharges an electricwave, and conversely restores the electric wave received from thetransponder 2 to take out a response signal.

The electric wave discharged from the interrogator 1 transmits not onlydata but also an electric power, which the transponder 2 requires.

The transponder 2 includes an antenna 21 and an IC tip 22 integrallyconstructed, and receives the electric wave from the interrogator 1 withthe antenna 21 to generate excitation voltage, thereby obtaining a powersupply for its operation by rectifying the excitation voltage.

Moreover, the transponder 2 restores the received electric wave to takeout a read signal, and modulates a response signal to re-discharge theelectric wave without amplifying the electric power. The multi-readsystem of multiple IDs is a system in which the interrogator 1 specifiesa read range of ID when transmitting a read signal, and the transponder2 returns its ID if it is within the given read range.

The transponder 2 does not voluntarily send a response signal, butpassively send it upon correctly recognizing the read signal receivedfrom the interrogator 1.

Consequently, the transponder 2 does not make a response in both caseswhen its ID is not within the given read range and when it cannotrecognize the given read signal. Therefore, when multiple transponders 2exist in the communication area of the interrogator 1, the read range ofID is so controlled that an unnecessary response is stopped and thatinterference and collision of the responses from the multipletransponders 2 are prevented.

FIGS. 2 and 3 show flow charts of preferred embodiments of the methodfor multi-reading a plurality of IDs according to the present invention.

FIG. 2 shows the case where the transponder 2 returns its ID to a queryfrom the interrogator 1, and FIG. 3 shows the case where the transponder2 returns only a response signal to a query from the interrogator 1.Upon starting the process, the interrogator 1 firstly specifies themaximum read range (S₀, e₀) in which IDs to be read may exist. (StepS1).

In order that the method for multi-reading according to the presentinvention makes the size of the read range d fluctuate in proportion tothe power of 2, the size of the read range d is defined as d=2^(e) foran easy operation, and the read range (S, e) is specified by the start Sof the read range and an exponent e of the size of the read range d. Atthis time, the end E of the read range is calculated by an equation,E=S+2^(e)−1.

Moreover, the exponent e expresses bit length of ID, for example, itmeans that e=16 corresponds to ID with 16 bits, e=32 corresponds to IDwith 32 bits, e=64 corresponds to ID with 64 bits, and e=128 correspondsto ID with 128 bits.

If the read range (S, e) is initially specified by the start S of theread range as S₀=1, and the exponent e as e₀=12, for example, the end Eof the read range will be E₀=1+2¹²−1=4096, and so the maximum read rangeinitially specified will be from 1 to 4096.

Alternatively, if the start S of the read range is initially specifiedas S₀=10001, for example, the minimum limit of the read range (S, e) canbe set at more than 10001. In addition to these means, the read rangemay be specified by setting the start S and the end E of the read range,or by setting the end E of the read range and the exponent e of the sizeof the read range d.

Next, the interrogator 1 transmits a read request command to thetransponder 2 (Step S2). When the read request command is transmitted,the transponder 2 calculates the end E of the read range by an equationE=S+2^(e)−1 with reference to the read range (S, e) of the read requestcommand so as to judge whether its ID is within the read range (S≦ID≦E),and when it is within the read range, the transponder 2 responds its ID(or a response signal in the case of FIG. 3) (Step S3).

Then, the interrogator 1 judges whether there is any response from thetransponder 2 (Step S4): when there is no response, it progresses toStep S9, and when there is one or more responses, it judges whether theresponse(s) is/are from a single transponder 2 or multiple transponders2. (In the case of FIG. 3, the interrogator judges whether the exponente=0) (Step S5). Whether the response(s) is/are a singular or plural canbe judged by checking a cyclic check code (CRC) etc, since a disorderarises in a bit pattern of the received signal when plural responsesoverlap: when an error is detected in the bit pattern, it is judged thatthere were plural responses.

When the interrogator 1 recognizes multiple responses in Step S5 (whenit detects the exponent e≠0 in the case of FIG. 3), it updates theexponent e of the read range (S, e) to e′ (the exponent afterupdating)=e (the exponent before updating)−1 (Step S6), and also sets aprevious response flag F to “multiple responses received” (to “singleresponse received” in the case of FIG. 3) (Step S7), then returns toStep S2 to transmits the subsequent read request command.

By the processing of Step S6, the read range (S, e) in the subsequentread request command is set to d′ (the size of the read range afterupdating)=d (the size of the read range before updating)/2 as shown inFIG. 4 (a), reducing the size of the read range d by half than theprevious time. Accordingly, E′ (the end of the read range afterupdating) is shifted down from E (the end of the read range beforeupdating) by the size of the read range d/2 only.

When the interrogator 1 recognizes a single response in Step S5 (whendetects the exponent e=0 in the case of FIG. 3), it reads out ID of thetransponder 2 which responded (Step S8), and updates the start S of theread range (S, e) to S′ (the start of the read range after updating)=S(the start of the read range before updating)+d (=2^(e)) (Step S9).

Then, S′ (the start of the read range after updating) is compared withE₀, the end of the read range initially specified as E₀=S₀+2^(e0)−1(Step S10), and if it is S′≧E₀, it is judged that the read rangeinitially specified is all searched and the interrogator 1 terminatesits operation.

If it is not S′≧E₀, the interrogator 1 determines whether the previousresponse flag F is set to “multiple responses received” (or “singleresponse received” in the case of FIG. 3) (Step S11), and when it is“multiple responses received”(or “single response received” in the caseof FIG. 3), the interrogator 1 resets the previous response flag F (StepS12) and returns to Step S2 to transmits the subsequent read requestcommand.

By the processing of Step S9, the read range (S, e) in the subsequentread request command is set to S′ (the start of the read range afterupdating)=S (the start of the read range before updating)+d, as shown inFIG. 4 (b), and the start of the read range S is shifted up only for thesize of the read range d than the previous time. At this time, it turnsout that S′=S+d=E+1 since the end of the read range E=S+d−1, i.e. S′(the start of the read range after updating) is shifted to the positionwhere 1 is added to E (the end of the read range before updating).Accordingly, E′ (the end of the read range after updating) is alsoshifted up only for the size of the read range d from E (the end of theread range before updating).

When the previous response flag F is not set to “multiple responsesreceived” (or “single response received” in the case of FIG. 3) in StepS11, the interrogator 1 updates the exponent e of the read range (S, e)to e′ (the exponent after updating)=e (the exponent before updating)+1(Step S13), and then returns to Step S2 to transmit the subsequent readrequest command.

By the processing of Step S13, the read range (S, e) in the subsequentread request command is set to d′ (the size of the read range afterupdating)=2d (the size of the read range before updating) as shown inFIG. 4 (c), and the size of the read range d is expanded twice than theprevious time.

Accordingly, E′ (the end of the read range after updating) is shifted uponly for the size of the read range 2d from E (the end of the read rangebefore updating). In addition, although the discrimination of IDs in theabove explanation is performed by shifting the read range (S, e) inascending order, it can be also performed in the opposite way byshifting the read range (S, e) in descending order.

More particular processing sequence chart of the method formulti-reading a plurality of IDs is shown in FIG. 5. In this embodiment,IDs of five transponders 2 selected at random are read in order, andeach of the IDs is referred to as 7, 58, 96, 145, and 208, respectively.The transponders 2 return their IDs to the query from the interrogator1.

The interrogator 1 specifies the read range (S=1, e=8) first. This makesthe end of the read range E₀=S₀+2^(e0)−1=1+2⁸−1=256, and theinterrogator 1 transmits the read request command for the read ranges1˜256 to the transponders 2. All the transponders 2 respond to thiscommand.

Then the interrogator 1, having received multiple responses, changes theexponent e to e−1=7, and specifies the read range (S=1, e=7). This makesthe end of the read range E=S+2^(e)−1=1+2⁷1=128, and the interrogator 1transmits the read request command for the read ranges 1˜128 to thetransponders 2. The transponders 2 referred to as 7, 58, and 96 respondto this command.

The interrogator 1, having received multiple responses again, changesthe exponent e to e−1=6, and specifies the read range (S=1, e=6). Thismakes the end of the read range E=S+2^(e) −1=1+2⁶−1=64, and theinterrogator 1 transmits the read request command for the read ranges 1˜64 to the transponders 2. The transponders 2 referred to as 7 and 58respond to this command.

Next, the interrogator 1, yet having received multiple responses,changes the exponent e to e−1=5, and specifies the read range (S=1,e=5). This makes the end of the read range E=S+2^(e)−1=1+2⁵−1=32, andthe interrogator 1 transmits the read request command for the readranges 1˜32 to the transponders 2. The transponder 2 referred to as 7only responds to this command.

Since the interrogator 1 now has a single response here, it reads out 7as a detection number and changes the start of the read range S toS=S+2^(e)=1+2⁵=1+32=33 so as to specify the read range (S=33,e=5). Thismakes the end of the read range E=S+2^(e)−1=33+2⁵−1=64, and theinterrogator 1 then transmits the read request command for the readranges 33˜64 to the transponders 2. The transponder 2 referred to as 58only responds to this command.

Since the interrogator 1 has a single response, it reads out 58 as adetection number, and changes the start of the read range S toS=S+2^(e)=33+2⁵=33+32=65. Moreover, since the previous response flag Fis not set to “multiple responses received”, the interrogator 1 thenchanges the exponent e to e+1=6 and specifies the read range (S=65,e=6). This makes the end of the read rangeE=S+2^(e)−1=65+2⁶−1=65+64−1=128, and the interrogator 1 then transmitsthe read request command for the read ranges 65˜128 to the transponders2.

The transponder 2 referred to as 96 only responds to this command. Sincethe interrogator 1 has a single response, it reads out 96 as a detectionnumber, then changes the start of the read range S toS=S+2^(e)=65+2⁶=65+64=129.

Moreover, since the previous response flag F is not set to “multipleresponses received”, the interrogator 1 then changes the exponent e toe+1=7, and specifies the read range (S=129, e=7). This makes the end ofthe read range E=S+2^(e)−1=129+2⁷−1=129+128−1=256, and the interrogator1 then transmits the read request command for the read ranges 129˜256 tothe transponders 2. The transponders 2 referred to as 145 and 208respond to this command.

Next, the interrogator 1, having received multiple responses, changesthe exponent e to e−1=6 and specifies the read range (S=129, e=6). Thismakes the end of the read range E=S+2^(e) −1=129+2⁶−1=192, and theinterrogator 1 then transmits the read request command for the readranges 129˜192 to the transponders 2. The transponder 2 referred to as145 only responds to this command.

Since the interrogator 1 now has a single response, it reads out 145 asa detection number, and then changes the start of the read range S toS=S+2^(e)=129+2⁶=129+64=193 so as to specify the read range (S=193,e=6). This makes the end of the read range E=S+2^(e) −1=193+2⁶−1=256,and the interrogator 1 then transmits the read request command for theread ranges 193˜256 to the transponders 2. The transponder 2 referred toas 208 only responds to this command. Since the interrogator 1 now has asingle response, it reads out 208 as a detection number, and thenchanges the start of the read range S to S=S+2^(e) =193+2⁶=193+64=257.The start of the read range S=257 thereby exceeds the end of the readrange E₀=256 as initially specified, thus all reading processes arecompleted at this point.

Industrial Applicability

According to the present invention as explained above, the interrogatordoes not query the symbols 1/0 of each bit of ID one by one as in theconventional method, but it specifies the read range and queries onlywhether ID is within the read range or not, so it is not necessary torepeat a query repeatedly with the present invention. Since one query issufficient with the present invention, discernment of ID can beperformed efficiently in a short time irrespective of a bit length ofID.

Moreover, the interrogator does not selectively forbid a response fromthe transponders whose bit code of IDs do not agree as in theconventional method, but forbids responses from the transponders whoseIDs are out of the read range all together. Therefore, a write-inprocessing on the transponders is not needed, thereby reducing costs foradditional parts and overhead required for the write-in processing.

Furthermore, the process of searching IDs according to the presentinvention only consists of a step of shifting the read range to thesubsequent rank in accordance with responses from the transponders, anda step of reducing the size of the read range by half or expanding ittwice so that ID can be searched by the binary search method with aprogram of simple loop structure.

Generally, when programming searching process of ID by the binary searchmethod, it is necessary to record history information in the process ofsubdividing the read range, and after completing the process with thesubdivided read range, it is necessary to return control to the originalread range with reference to this history information. For this reason,processing logic becomes complicated and a large amount of memories andCPUs are consumed in order to manage the history of the read range.

Moreover, when not managing the history information by the program, itbecomes so-called recursive call structure program using recursive subroutine which calls itself. For this reason, program structure becomescomplicated, and the overhead for evacuating and recovering the historyinformation increases every time the sub routine is called, therebyelongating the processing time.

Consequently, according to the present invention, an efficientprocessing program whose structure is simple, processing step is short,and consumption of a memory and CPU is small is realized. Moreover,since the present invention searches ID by shifting the read range inascending or descending orders, IDs are detected in ascending ordescending orders thereby getting rid of a sorting process after thesearching operation.

Moreover, since the present invention defines the size of the read rangeby 2^(e), i.e. the power of 2, it will only need 3 bits to specify64-bit ID with the exponent e as 2⁶=64, which would otherwise need whole64 bits. Thus, the amount of data to transmit at a query is sharplyreducible.

Furthermore, the present invention allows a high-speed operation by theshift register, since calculation of the reduction value (d/2) of thesize of the read range d or the expansion value (2×d) of the size of theread range d can be calculated by an easy subtraction and addition.

1. A method for multi-reading a plurality of IDs, wherein aninterrogator and multiple transponders repeat queries and responsestherebetween in order that the interrogator discriminates unique IDgiven to each one of the transponders; and wherein said interrogatorwhen querying specifies a read range of IDs and permits a response fromonly the transponders whose IDs are within said read range.
 2. Themethod for multi-reading a plurality of IDs as described in claim 1,wherein said transponders when responding return their IDs, comprisingthe steps of: 1) when there is a plurality of responses to the query ofsaid interrogator, reducing the size of said read range by half in thesubsequent query; 2) when there is a single response to the query ofsaid interrogator, reading out ID of the transponder which responded aswell as shifting said read range to the following rank in the subsequentquery; and further when there is a single response or no response to theprevious query, expanding the size of said read range d twice; and 3)when there is no response to the query of said interrogator, shiftingsaid read range to the following rank in the subsequent query; andfurther when there is a single response or no response to the previousquery, expanding the size of said read range d twice; whereby the abovementioned steps are repeated until searching of all the read ranges inwhich IDs to be read may exist is completed.
 3. The method formulti-reading a plurality of IDs as described in claim 1, wherein saidtransponders when responding returns only response signals, comprisingthe steps of: 1) when there is a response/responses from saidtransponders to the query of said interrogator, and 1.1) when the sizeof said read range d is not equal to 1, reducing the size of said readrange d by half in the subsequent query; 1.2) when the size of said readrange d is equal to 1, reading out ID of the transponder which respondedas well as shifting said read range to the following rank in thesubsequent query; and further when there is a response/responses to theprevious query and the size of said read range d is equal to 1 or whenthere is no response, expanding the size of said read range d twice; and2) when there is no response from said transponders to the query of saidinterrogator, shifting said read range to the following rank in thesubsequent query; and further when there is a response/responses to theprevious query and the size of said read range d is equal to 1 or whenthere is no response, expanding the size of said read range d twice;whereby the above mentioned steps are repeated until searching of allthe read ranges in which IDs to be read may exist is completed.
 4. Themethod for multi-reading a plurality of IDs as described in claim 2,wherein the size of said read range d is defined by 2^(e), i.e. thepower of 2, and said read range d is specified by an integer value ofeither the start S or the end E of said read range d and exponent e ofsaid read range d.
 5. The method for multi-reading a plurality of IDs asdescribed in claim 4, wherein the reduction value (d/2) of the size ofsaid read range d is calculated by exponential function, e=e−1.
 6. Themethod for multi-reading a plurality of IDs as described in claim 4,wherein the expansion value (2×d) of the size of said read range d iscalculated by exponential function, e=e+1.
 7. The method formulti-reading a plurality of IDs as described in claim 4, wherein theend E of said read range is calculated by formula E=S+2^(e)−1 when saidread range is specified by the start S of said read range and theexponent e.
 8. The method for multi-reading a plurality of IDs asdescribed in claim 4, wherein the start S of said read range iscalculated by formula S=E−2^(e)+1, when said read range is specified bythe end E of said read range and the exponent e.
 9. The method formulti-reading a plurality of IDs as described in claim 3, wherein thesize of said read range d is defined by 2^(e), i.e. the power of 2, andsaid read range d is specified by an integer value of either the start Sor the end E of said read range d and exponent e of said read range d.10. The method for multi-reading a plurality of IDs as described inclaim 9, wherein the reduction value (d/2) of the size of said readrange d is calculated by exponential function, e=e−1.
 11. The method formulti-reading a plurality of IDs as described in claim 9, wherein theexpansion value (2×d) of the size of said read range d is calculated byexponential function, e=e+1.
 12. The method for multi-reading aplurality of IDs as described in claim 9, wherein the end E of said readrange is calculated by formula E=S+2^(e)−1 when said read range isspecified by the start S of said read range and the exponent e.
 13. Themethod for multi-reading a plurality of IDs as described in claim 9,wherein the start S of said read range is calculated by formula S=E−2^(e)+1, when said read range is specified by the end E of said readrange and the exponent e.